Method and apparatus for treating strip material



7, 1962 w. w. KOMPART 3,048,504

METHOD AND APPARATUS FOR TREATING STRIP MATERIAL Original Filed Feb. 14, 1952 FIG.I.

23 INVENTOR WALTER W. KOM PART ATTORNEY 3 043.5% METHGD AND APP ARATUS FBR TREATME- STRIP MATERIAL Walter W. Kornpart, Conneant, @hlo, assignor to National Steel (forparation, a corporation of Delaware Continuation of abandoned application Ser. No. 271,529, Feb. 14, 1952. This application .l'an, 23, 13 58 Ser. No. 71%,73!)

11 Cl ms. (Cl. 134-15) The present invention relates to improvements in treating strip material where the strip material is rapidly moved downstream across a bath of strip treating liquid, in a tank so that the moving strip pulls liquid along and raises the level of the bath at the downstream end of the tank and more particularly relates to lowering the level at the downstream end of the bath by collecting liquid at the downstream end of the bath and returning the collected liquid to the bath at a point upstream to increase circulation throughout the bath.

The present invention will be described more particularly in connection with the continuous pickling or etching of ferrous metal strip moving at high speed through an electroplating line. The strip, prior to being electroplated, is passed at high speed across a bath containing an acid such as sulfuric or hydrochloric acid to clean the strip so that the strip will present a clean surface. The present invention is not limited to continuously pickling or cleaning ferrous metal strip and the principles of the present invention are applicable to other Q strip materials, to other types of treatment, to alkaline cleaning baths, and to other pickling acid baths.

When continuously pickling ferrous metal strip, for

example strip blackplate, the strip is passed at high speed across a pickling bath confined in a long tank. The 3 rapidly moving strip pulls solution along with it toward the exit end of the tank and raises the level of the solution at the exit end. The speed of the strip is limited to a speed below which solution is piled up to a level at which solution will flow out of the tank. While various proposals have been made for returning solution to the entry end of the pickling bath by means of a suitable pump, such a pumping system and the required collecting system is quite complicated to install and maintain. This problem of the rise in level of liquid at the downstream end of the tank is particularly acute in high speed pickling lines and electroplating lines and in mills for continuously rolling strip and the like.

An object of the present invention is to provide a method and apparatus for preventing liquid from flowr ing out of a tank when a strip is moved at high speed across the tank in contact with a bath of liquid in the tank.

Another object of the present invention is to provide an improved method and apparatus for collecting liquid flowing out of a bath and for returning the collected solution to the bath by gravity flow.

Another object of the present invention is to provide an improved method and apparatus for collecting liquid piled up at the downstream end of a bath by a strip moved at high speed across the bath and for returning this collected solution to the upstream end of the bath so as to maintain the bath constituents uniform throughout all portions.

Patented Aug. 7, 1362 Another object of the present invention is to provide an improved apparatus for treating strip material.

Another object of the present invention is to provide an improved tank apparatus for treating strip in which the tank sidewalls are reinforced by a tank dividing Wall which also functions as part of the means for returning liquid to the bath in the tank.

In accordance with the present invention, the pickling solution pulled along by the strip down to the down stream end of the bath is collected and returned upstream to the pickling bath, preferably at the upstream end of the bath, by gravity flow. The gravity flow of the pickling solution eliminates the need for a complicated pumping system and flowing solution to the upstream end of the pickling bath recirculates the bath and maintains the bath uniform throughout all portions.

in one embodiment of the present invention, a pickling tank is provided with a horizontal dividing wall extending between the side Walls and spaced above the bottom of the tank so as to divide the tank into upper and lower compartments. This dividing wall terminates at points spaced from the upstream and downstream ends of the tank. A bafile extends upwardly from the downstream end of the dividing wall. The strip is moved through the bath in the upper compartment and then across the top of the battle. The bath solution is piled up against the bafile and the solution flowing across the top of the baille is collected on the downstream side of the bafile and then llows by gravity through the lower compartment beneath the dividing wall and back into the upper compartment past the upstream end of the dividing wall. The solution is constantly returned to the upstream end to maintain the bath substantially constant and the strip can be moved across the tank at high speeds.

These and other objects and advantages will become more readily apparent when considering the following description, taken with the accompanying drawings, in which:

FIGURE 1 is a longitudinal sectional view of appara tus embodying the principles of the present invention; and

FIGURE 2 is a transverse sectional View taken along line 2-2 of FIGURE 1.

Referring to the drawings, the strip S is progressively and continuously moved across the tank T by suitable roll means which may be of the type customarily used in mills for moving a strip through a treating line. As shown, the strip S passes between a pair. of rolls 12 and 13, then downwardly beneath a guide roll 14, then across the tank and beneath a second guide roll 16 and then upwardly and out of the tank between a pair of squeeze rolls 17 and 18. The squeeze rolls 17 and 18 prefeia bly are rubber covered and squeeze the. strip therebetween and remove liquid dragged along on the strip surfaces. The other rolls may be covered with rubber to protect them against attack by the pickling solution. All of the rolls 1?; to 18, inclusive, are rotatably mounted, and the rolls may be driven, it desirable, by any suitable means, not shown.

The tank T may include an outer metal tank or shell Zll which may be lined with bricks or blocks 21 which are resistant to attack by the liquid in the tank. Tank T includes a bottom Wall 23, oppositely spaced apart side walls 24, an entry end wall 25 and an exit wall 26.

The tank T is adapted to contain a bath. of strip treatw ing liquidfor example, a bath of sulfuric acid pickling solution. In operation, the strip passes between rolls l2 and 13, then downwardly beneath roll 14 and across the bath to roll 16 and then upwardly and out of the bath and between rolls 17 and 13. As the strip is moved across the tank, the strip moves along a path having a first portion extending from the entry end rolls 12 and 13 to guide roll 14, with this portion of the path extending downwardly into the tank at the entry end. The strip then moves along a second portion of the path extending across the bath of pickling solution and from guide roll 14 to guide roll 16. After the strip has moved along this second portion of the path, it moves along a third portion of the path extending from guide roll 16 to squeeze rolls l7 and 18 so that this third portion of the path extends upwardly and out of the bath and the tank. Preferably, the squeeze rolls 17 and 18 are positioned so that solution removed by the squeeze rolls falls down into the tank. The path of the strip S between guide 1 rolls 14 and 16 is horizontal, but this portion of the path need not be horizontal as long as the strip is in contact with the bath throughout the required distance of its travel across the bath.

As described so far, tank T and the rolls are of customary construction. As the strip is moved across the tank T, the strip tends to pull solution downstream toward the exit end of the tank so that the level of solution is higher at the downstream or exit end of the tank than at the upstream or entry end of the tank. The rapidly moving strip may pile up the solution against wall 26 and raise the solution level above the top of wall 26 so that solution will fiow out of the tank. A strip moving, for example, at a speed of 1,000 to 2,000 feet per minute, or faster, pulls along a large quantity of solution. Thus, the speed of the strip is limited to that speed at which solution does not flow out of the tank.

In accordance with the present invention, means are provided in the tank T for preventing the solution from piling up against the wall 26. Means preferably is provided for collecting the solution pulled along by the strip and tending to pile up against wall 26 and for flowing this collected solution into the pickling bath. A dividing wall 28 extends across the tank T between the sidewalls 24 and the dividing wall 28 is spaced above the bottom wall 23 to divide the tank into an upper compartment 29 and a lower passage or compartment 30. The dividing wall 28 has its ends spaced from the end walls 25 and 26 to provide openings at 31 and 32. A baffle 33 extends between the sidewalls 24- and extends ,upwardly from the dividing wall 28 between the openings 31 and 32. The bafile 33 has an upper edge 34 positioned below the path of the strip where it moves upwardly and out of bath 35. The upper edge portion 34 is at a level higher than the level of the strip as it moves across the bath 35 between guide rolls l4 and 16 and is below the top of the sidewalls. The bafile 33, together with the portion of the tank T at the downstream or exit end, define a vertical passage 36 having an inlet at 37 which is above the level of the strip as it moves across the bath 35. The bottom wall 23 of the tank T and the dividing wall 28, together with portions of the sidewalls 24, define the lower compartment 30 which also is a passage having an outlet at 31 opening into the upper compartment 29. The downwardly extending passage 36 and the rearwardly extending passage 30 are connected at 32 and together define a continuous passage having an inlet at 37 and an outlet at 31.

As the strip S moves across the tank T, it pulls liquid toward the exit end. Without the baflle 33, the solution would pile up against the exit end wall 26, and, if the strip were moving too fast, a large quantity of liquid would flow out of the tank. The faster the strip moves, the more solution piles up against wall 26. Thus, if the strip moves toofast, solution will flow over wall 26 and under some conditions, the solution may pile up against wall 26 sufficiently to unduly lower the liquid level at the entry end.

With the dividing wall 28 and bafile 33, or their equivalent, in place, the solution pulled along by the strip piles up against the upper portion of bafile 33 and quickly spills over the edge 34 and through inlet 37 of the collecting and returning passage. The bafile 33 prevents the solution from piling up against the wall 26. As the solution flows into passage 36 through inlet 37, the level tends to rise in passage 36, and as this level rises above the level of the solution in the entry end of the tank, solution fiows by gravity through passages 36 and 30and then through outlet 31 into the bath of liquid 35 in the inner compartment of the tank. Under any one set of conditions, a state of equilibrium is quickly reached,

and there is a continuous recirculation of solution to the pickling bath, and the rapidly moving strip will not pile solution up against wall 26. The only solution removed from the tank will be the thin film left on the strip surfaces by the squeeze rolls l7 and 18.

As shown more clearly in FIGURE 2, the wall 28' may be made of bricks or blocks resistant to attack by the acid. Preferably, the wall 23 is arched and extends between the side walls 24 to form an arch reinforcing the brick inner walls of walls 24.

While I have described a preferred form of apparatus, it is obvious that modifications may be made within the spirit of my invention. The tank may be formed of other materials, and the rolls 14 and 16 may be positioned to maintain the strip at other levels with substantially only the bottom surface of the strip in contact with the bath 35 or to submerge the strip more deeply in the bath 35.

This application is a continuing application of applicants copending application Serial No. 271,529, filed February 14, 1952, now abandoned.

What is claimed is:

1. In the treating'of continuous strip material, in which treatment the strip material is moved at high speed along a continuous path across a bath of treating liquid contained in a tank from the entry end of the tank to the exit end of the tank; the continuous path including a first portion extending into the tank adjacent its entry end to a level below the upper edge of the tank, a second portion located in the bath of liquid and extending longitudinally of the tank and a third portion extending upwardly and out of the bath in a direction toward the exit end of the tank to a level abovethe upper edge of the tank; the strip material moving at high speed along the continuous path pulling liquid in the direction of strip travel and raising the liquid at the exit end of the tank to a level above the level of the liquid at the entry end of the tank, the liquid being pulled upwardly and toward the exit end of the tank along the third portion of the continuous path, the method of conducting raised liquid at the exit end of the tank to the bath upstream of the exit end of the tank comprising the steps of diverting liquid pulled by the strip material along the third portion of the continuous path in a substantially downwardly direction, conducting the diverted liquid downwardly to a re ion at a level below the second portion of the continuous path and then through a confined path to a second region located upstream of the exit end of the tank and below the level of the second portion of the continuous path, the confined path being located below the level of the second portion of the continuous path and extending from the first region to the second region, and introducing the diverted liquid into the bath at said second region.

2. In the treating of continuous strip material, in which treatment the strip material is moved at high speed along a continuous path across a bath of treating liquid contained in a tank from the entry end of the tank to the exit end of the tank; the continuous path including a first portion extending into the tank adjacent its entry end to a level below the upper edge of the tank, a second portion located in the bath of liquid and extending longitudinally of the tank and a third portion extending upwardly and out of the bath in a direction toward the exit end of the tank to a level above the upper edge of the tank; the strip material moving at high speed along the continuous path pulling liquid in the direction of strip travel and raising the liquid at the exit end of the tank to a level above the level of the liquid at the entry end of the tank; the method of lowering the level of the liquid at the exit end of the tank downstream of the second portion of the continuous path which comprises collecting in a first region raised liquid downstream of the second portion of the continuous path, the first region being located at a level above the level of the second portion of the continuous path and below the upper edge of the tank, forming a stream of collected liquid, conducting the stream of collected liquid from the first region downwardly to a confined path located below the level of the second portion of the continuous path and along the confined path to a second region located upstream of the exit end of the tank and below the level of the second portion of the continuous path and introducing the stream into the path at the second region, the liquid stream being conducted from the first region to the second region by a force including a pressure determined by the difference of the liquid heads at the first and second regions and the stream of collected liquid tlowing downwardly and longitudinally of the tank in countercurrent relation with the liquid being pulled downstream by the strip material upon its conduction from the first region to the second region.

3. in the treatment of continuous strip material, in which treatment the strip material is moved at high speed along a continuous path across a bath of treating liquid contained in a tank from the entry end of the tank to the exit end of the tank; the continuous path including a first portion extending into the tank adjacent its entry end to a level below the upper edge of the tank, a second portion located in the bath of liquid and extending longitudinally of the tank and a third portion extending upwardly and out of the bath in a direction toward the exit end of the tank to a level above the upper edge of the tank; the strip material moving at high speed along the continuous path pulling liquid downstream in a direction toward the exit end of the tank and raising the level of the liquid downstream of the second portion of the continuous path to a level above the level of the liquid upstream of the second portion of the continuous path, the method of preventing liquid pulled downstream by the strip material from piling up against the exit end of the tank and of lowering the level of the liquid downstream of the second portion of the continuous path which comprises diverting in a first region downstream of the second portion of the continuous path and upstream of the exit end of the tank the flow of liquid material pulled down stream by the strip material from the direction toward the exit end of the tank, the first region being located above the level of the second portion of the continuous path and beneath the third portion of the continuous path and below the upper edge of the tank at itsexit end, collecting diverted liquid raised to a level above the level of the liquid at the entry end of the tank, forming a stream of collected liquid, conducting the stream of collected liquid downwardly to a level below the level of the second portion of the continuous path and then longitudinally of the tank in a direction toward the entry end of the tank in countercurrent relation with the liquid pulled downstream by the strip material to a second re ion at a level below the level of the second portion of the continuous path and upstream of the second portion of the continuous path, and introducing the stream into the bath at the second region, the stream of collected liquid being conducted to the second region and into the bath by a force including a pressure determined by the difference of the liquid head of the collected liquid and the liquid head of the bath at the second region.

4. In the treatment of continuous strip material, in which treatment the strip material is moved at high speed along a continuous path across a bath of treating liquid contained in a tank from the entry end of the tank to the exit end of the tank; the continuous path including a first portion extending into the tank adjacent its entry end to a level below the upper edge of the tank, a second portion located in the bath of liquid and extending longitudinally of the tank and a third portion extending upwardly and out of the bath in a direction toward the exit end of the tank to a level above the upper edge of the tank; the strip material moving at high speed along the continuous path pulling liquid in the direction of strip travel and raising the liquid at the exit end of the tank to a level above the level of the liquid at the entry end of the tank; the combination of means for lowering the level of the liquid at the exit end of the tank downstream of the second portion of the continuous path comprising aliquid collector located downstream of the second portion of the continuous path at a level above the level of the second portion of the continuous path and below the upper edge of the tank for collecting raised liquid at the exit end of the tank, liquid introducing means located upstream of the exit end of the tank and below the level of the second portion of the continuous path for introducing liquid into the bath, means forming a stream of collected liquid, and means forming a confined path connected between the last-named means and the liquid introducing means and located below the level of the second portion of the confined path, the confined path conducting the stream of collected liquid from the liquid collector longitudinally of the tank in countercurrent relation with the liquid being pulled downstream by the strip material to the liquid introducing means by a force including a pressure determined by the difference of the liquid heads at the liquid collector and at the introducing means.

5. In apparatus for treatment of continuous strip mate rial; a tank adapted to contain a bath of treating liquid; means for guiding strip material along a continuous path including a first portion extending into the tank adjacent its entry end to a level below the upper edge of the tank, a second portion located in the bath of liquid and extending longitudinally of the tank and a third portion extending upwardly and out of the bath in a direction toward the exit end of the tank to a level above the upper edge of the tank; means for moving the strip material at high Speed along the continuous path in a direction from the entry end of the tank to the exit end of the tank so that the strip material pulls liquid downstream in a direction toward the exit end of the tank and raises the level of the liquid downstream of the second portion of the continuous path to a level above the level of the liquid upstream of the second portion of the continuous path to a level above the level of the liquid upstream of the second portion of the continuous path; and means for preventing liquid pulled downstream by the strip material from piling up against the exit end of the tank and for lowering the level of the liquid downstream of the second portion of the continuous path; the last-named means comprising liquid diverting means located at the exit end of the tank above the level of the second portion of the continuous path and beneath the third portion of the continuous path and below the upper edge of the tank for diverting away from the exit end of the tank liquid pulled downstream by the strip material, means collecting liquid diverted by the liquid diverting means, liquid introducing means located upstream of the exit end of the tank and below the level of the second portion of the continuous path for introducing liquid into the bath, means forming a stream of collected liquid, means conducting a stream of collected liquid downwardly to a level below the level of the second portion of the continuous path and longitudinally of the tank in a direction toward the entry end of the tank in countercurrent rela spas, 504

tion with liquid pulled downstream by the strip material to the liquid introducing means by a force including a pressure determined by the difference of the liquid head of the collected liquid and the liquid head of the bath at the liquid introducing means.

6. ln apparatus for continuously treating elongated strip material comprising tank means having spaced apart upwardly extending side walls and upwardly extending end walls joined to the side walls at the entry end and at the exit end of the tank means for confining a bath of treating liquid; means for guiding strip material longitudinally of the tank means along a continuous path including a first portion extending into the tank means between the side walls of the tank means adjacent the entry end of the tank means to a lower level below the upper edge of the walls of the tank means, a second portion extending along the tank means between the side walls in contact with the treating liquid at a level corresponding substantially to the lower level and a third portion inclined upwardly from the lower level in a direction toward the exit end of the tank means out of contact with the treating iquid and to a level above the upper edge of the exit end wall of the tank means; means for moving the strip material along the confined path in a direction from the entry end of the tank means to the exit end of the tank means at high speed so that the strip material pulls liquid in the direction of strip travel and raises the level of the liquid downstream of the second portion of the continuous path above the level of the liquid at the entry end of the tank means; and means for controlling the flow of raised liquid downstream of the second portion of the continuous path and for collecting raised liquid and returning collected liquid to the bath upstream of the exit end of the tank means; the last-named means comprising means forming a passageway extending longitudinally of the tank means and having an inlet communicating with the tank means in a region adjacent the exit end of the tank means and an outlet communicating with the tank means in a region upstream of the exit end of the tank means, the passageway and the regions of communication of its inlet and its outlet with the tank means being located at a level below the lower level of the second portion of the continuous path, and baffle means located in the tank means in the region of the passageway inlet downstream of the second portion of the continuous path and in spaced relation with the exit wall and extending transversely of the tank means, the balile means extending upwardly from a level below the lower level of the second portion of the continuous path and ineluding a portion extending transversely of the continuous path and extending upwardly into the path of the raised liquid and terminating below the upper edge of the exit wall of the tank means and beneath the third portion of the continuous path, the baflie means preventing liquid pulled along the tank means in the direction of the moving strip material from piling up against the exit end wall tween the side walls of the tank means adjacent the entry to a lower level below the upper edge of the walls of the tank means, a second portion extending along the tank means between the side walls in contact with the treating liquid at a level corresponding substantially to the lower level and a third portion inclined upwardly from the lower level in a direction toward the exit end of the tank means out of contact with the treating liquid to a level above the upper edge of the exit end wall of the tank means; means for moving strip material along the confined path in a direction from the entry end to the exit end of the tank means at high speed so that the strip material pulls liquid in the direction of strip travel and raises the level of the liquid downstream of the second portion of the continuous path above the level of the liquid at the entry end into the tank means; and means for c011 trolling the flow of raised liquid downstream of the sec ond portion of the continuous path and for collecting raised liquid and returning collected liquid to the bath upstream of the exit end of the tank means; the last-named means comprising means forming a passageway extending longitudinally of the tank means and having an inlet communicating with the tank means in a region adjacent the exit end of the tank means and an outlet communicating with the tank means in a region upstream of the exit end of the tank means, the passageway and the regions of communication of its inlet and its outlet with the tank means being located at a level below the lower level of of the tank means, and the battle means forming an extension of the passageway inlet adjacent the exit end of the tank means from a level below the lower level of the second portion of the continuous path to a level above the lower level of the second portion of the continuous path so that raised liquid at the exit end of the tank means flows into the extension of the passageway inlet and the liquid flowing into the extension produces a pressure head forcing liquid into the passageway inlet, through the passageway and from the passageway outlet into the tank 1 means at the region upstream of its exit end.

7. In apparatus for continuously treating elongated strip material comprising tank means having spaced apart upwardly extending side walls and upwardly extending end walls joined to the side walls at the entry end and at the exit end of the tank means for confining a bath of treating liquid; means for guiding strip material longitudinally of the tank means along a continuous path including a first portion extending into the tank means hethe second portion of the continuous path, and bafile means located in the tank means in the region of the passageway inlet downstream of the second portion of the continuous path and in spaced relation with the exit wall and extending transversely of the tank means, the bafile means extending upwardly from a level below thelower level of the second portion of the continuous path and including a portion extending transversely of the continuous path and extending upwardly beyond the lower level of the second portion of the continuous path in the region of the third portion of the continuous path to a higher level below the upper edge of the exit wall of the tank means and beneath the third portion of the continuous path and into the path of the raised liquid, the bafile means being disposed on the upstream side of a plane substantially perpendicular to the second portion of the continuous path and spaced from the exit end wall of the tank means, the baflie means forming an extension of the passageway inlet adjacent the exit end of the tank means from a level below the lower level of the second portion of the continuous path to a level above the lower level of the second portion of the continuous path so that raised liquid at the exit end of the tank means flows into the extension of the passageway inlet and the liquid flowing into the extension produces a pressure head forcing liquid into the passageway inlet, through the passageway and from the passageway outlet into the tank means in the region upstream of its exit end.

8. In apparatus for continuously treating elongated strip material comprising tank means having spaced apart upwardly extending side walls and upwardly extending end walls joined to the side walls at the entry end and at the exit end of the tank means for confining a bath of treating liquid; means for guiding strip material longitudinally of the tank means along a continuous path including a first portion extending into the tank means between the side walls of the tank means adjacent the entry into the tank means to a lower level below the upper edge of the walls of the tank means, a second portion extending along the tank means between the side walls in contact with the treating liquid at a level corresponding substantially to the lower level and a third portion inclined upwardly from the lower level in a direction toward the exit end of the tank means out of contact with the treating liquid and to a level above the upper edge of the exit end wall of the tank means; means for moving strip material at high speed along the conaoaaeoa fined path in a direction from the entry end of the tank means to the exit end of the tank means so that the strip material pulls liquid in the direction of strip travel and raises the level of the liquid downstream of the second portion of the continuous path above the level of the liquid at the entry end into the tank means; and means for controlling the iiow of raised liquid downstream of the second portion of the continuous path and for collecting raised liquid and returning collected liquid to the bath upstream of the exit end of the tank means; the last-named means comprising means forming a passageway extending longitudinally of the tank means and having an inlet communicating with the tank means at a region adjacent the exit end of the tank means and an outlet communicating with the tank means at a region adjacent the inlet end of the tank means, the passageway and the regions of communication of its inlet and its outlet with the tank means being located at a level below the lower level of the second portion of the continuous path, and baffle means extending upwardly from the passageway downstream of the second portion of the continuous path in spaced relation with the exit Wall of the tank means and extending transversely or" the tank means, the battle means including a portion extending transversely of the continuous path and extending upwardly beyond the lower level of the second portion of the continuous path in the region of the third portion of the continuous path and terminating in an upper edge portion located at a level above the lower level of the second portion of the continuous path and below the upper edge of the exit wail of the tank means and be heath the third portion of the continuous path and into the path of the raised liquid, the baffle means being disposed on the upstream side of a plane substantially perpendicular to the second portion of the continuous path and spaced from the exit end wall of the tank means and extendin along the depth of the tank means from a level below the level of the second portion of the continuous path to a level above the level of the second portion or" the continuous path, and the battle means forming an extension of passageway inlet at the exit end of the tank means from a level below the lower level of the second portion of the continuous path to a level above the lower level of the second portion of the continuous path so that raised liquid llows into the extension of the passageway inlet and the liquid flowing into the extension produces a pressure head forcing liquid into the passageway inlet, through the passageway and from the passageway outlet into the tank means in the region adjacent its entry end.

9. in apparatus for continuously treating elongated strip material comprising tank means having spaced apart upwardly extendin side walls and upwardly extending end walls joined to the side walls at the entry end and, at the exit end of the tank means for confining a bath of treating liquid; means for guiding strip material longitudinally of the tank means along a continuous path including a first portion extendin into the tank means between the side walls of the tank m ans adjacent the entry into the tank means and at a lower level below the upper edge of the walls of the tank means, a second portion extending along the tank means between the side walls in contact with the treating liquid at a level corresponding substantially to the lower level and a third portion inclined upwardly from the lower level in a direction toward the exit end of the tank means out of contact with the treating liquid and to a level above the upper edge of the exit end wall of the tank means; means for moving strip material at high speed along the confined path in a direction from the entry end of the tank means to the exit end of the tank means so that the strip material pulls liquid in the direction of strip travel and raises the level of the liquid downstream of the second portion of the continuous path above the level of the liquid at the entry end into the tank means; and means for controlling the flow of raised liquid downstream of the second portion of the continuous path and for collecting raised liquid and returning collected liquid to the bath upstream of the exit end of the tank means; the last-named means comprising baiile means located in the tank means downstream of the second portion of the continuous path in spaced relation with the exit end wall of the tank means and extending transversely of the tank means, the baffle means extending upwardly from a level below the lower level of the second portion of the continuous path and including a portion extending transversely of the continuous path and extending upwardly beyond the lower level of the second portion of the continuous path in the region of the third portion of the continuous path to a higher level below the upper edge of the exit wall of the tank means and beneath the third portion of the continuous path and into the path of the raised liquid, the battle means being disposed on the upstream side of a plane substantially perpendicular to the second portion of the continuous path and spaced from the exit end wall of the tank means, means definin a passageway extending longitudinally of the tank means having an inlet on the downstream side of the battle means at a level below the lower level of the second portion of the strip material and an outlet opening into the tank means at a region upstream of the baffle means and at a level below the lower level of the second portion of the continuous path, the baffle means and the passageway defining a gravity system for conducting raised liquid at the exit end of the tank means to the tank means upstream or" the battle means.

10. In apparatus for continuously treating elongated strip material comprising tank means having spaced apart upwardly extending side walls and upwardly extending end walls joined to the side walls at the entry end and at the exit end of the tank means for confining a bath of treating liquid; means for guiding strip material longitudinally of the tank means along a continuous path including a first portion extending into the tank means between the side walls of the tank means adjacent the entry into the tank means and at a lower level below the upper edge of the walls of the tank means, a second portion extending along the tank means between the side walls in contact with the treating liquid at a level corresponding substantially to'the lower level and a third portion inclined upwardly from the lower level in a direction toward the exit end of the tank means out of contact with the treating liquid and to a level above the upper edge of the exit end wall of the tank means; means for moving strip material at high speed along the confined path in a direction from the entry end of the tank. means to the exit end of the tank means so that the strip material pulls liquid in the direction of strip travel and raises the level of the liquid downstream of the second portion of the continuous path above the level or the liquid at the entry end into the tank means; and means for controlling the flow of raised liquid downstream of the second portion of the continuous path and for collecting raised liquid and returning collected liquid to the bath upstream of the exit end of the tank means; the last-named means comprising wall means extending across the tank means above the bottom wall and below the level of the second portion of the continuous path between the side walls for dividing the tank into relatively lower upper cornpartments, means in the entry end of the tank means definin a first passage between the compartments, means in the exit end of the tank means defining a second passage between the compartments, a baffle extending upwardly from the wall means downstream of the second portion of the continuous path and upstream of the second opening bet een the compartments in spaced relation with the exit end wall of the tank means and extending between the side walls, the baffie including a portion extending upwardly beyond the level of the second portion of the continuous path and terminating in an upper edge portion located below the third portion of the continuous path and into the path of the raised liquid, and the baffle being disposed on the upstream side or" a plane sub- '1 1 stantially perpendicular to the second portion of the con,- tinuous path and spaced from the exit end wall of the tank means, the hafile, the first passage, the lower compartment and the second passage forming a gravity system for conducting liquid pulled downstream by the moving strip material and flowing over the upper edge of the baffie at the exit end of the tank means into the bath upstream of the baffle.

11. In an apparatus for continuously treating strip material as defined in claim 10, in which the walls of the tank means are at least lined with brickwork and the Wall means is formed of brickwork extending in an arch 12 across the tank means and bracing the brickwork of the Walls.

References Cited in the file of this patent UNITED STATES PATENTS 1,837,159 Fellows Dec. 15, 1931 2,348,232 Trautman May 9, 1944 2,697,050 Barnes Dec. 14, 1954 2,728,629 Blomberg Dec, 27, 1955 FOREIGN PATENTS 449,551 Germany Sept. 15, 1927 

1. IN THE TREATING OF CONTINUOUS STRIP MATERIAL, IN WHICH TREATMENT THE STRIP MATERIAL IS MOVED AT HIGH SPEED ALONG A CONTINUOUS PATH ACROSS A BATH OF TREATING LIQUID CONTAINED IN A TANK FROM THE ENTRY END OF THE TANK TO THE EXIT END OF THE TANK; THE CONTINUOUS PATH INCLUDING A FIRST PORTION EXTENDING INTO THE TANK ADJACENT ITS ENTRY END TO A LEVEL FROM BELOW THE UPPER EDGE OF THE TANK, A SECOND PORTION LOCATED IN THE BATH OF LIQUID AND EXTENDING LONGITUDINALLY OF THE TANK AND A THIRD PORTION EXTENDING UPWARDLY AND OUT OF THE BATH IN A DIRECTION TOWARD THE EXIT END OF THE TANK TO A LEVEL ABOVE THE UPPER EDGE OF THE TANK; THE STRIP MATERIAL MOVING AT HIGH SPEED ALONG THE CONTINUOUS PATH PULLING LIQUID IN THE DIRECTION OF STRIP TRAVEL AND RAISING THE LIQUID AT THE EXIT END OF THE TANK TO A LEVEL ABOVE THE LEVEL OF THE LIQUID AT THE ENTRY END OF THE TANK, THE LIQUID BEING PULLED UPWARDLY AND TOWARD THE EXIT END OF THE TANK ALONG THE THRID PORTION OF THE CONTINUOUS PATH, THE METHOD OF CONDUCTING RAISED LIQUID AT THE EXIT END OF THE TANK TO THE PATH UPSTREAM OF THE EXIT END OF THE TANK COMPRISING THE STEPS OF DIVERTING LIQUID PULLED BY THE STRIP MATERIAL ALONG THE THIRD PORTION OF THE CONTINUOUS PATH IN A SUBSTANTIALLY DOWNWARDLY DIRECTION, CONDUCTING THE DIVERTED LIQUID DOWNWARDLY DIRECTION, CONDUCTING THE DIVERTED LIQUID DOWNOF THE CONTINUOUS PATH AND THEN THROUGH A CONFINED PATH TO A SECOND REGION LOCATED UPSTREAM OF THE EXIT END OF THE TANK AND BELOW THE LEVEL OF THE SECOND PORTION OF THE CONTINUOUS PATH, THE CONFINED PATH BEING LOCATED BELOW THE LEVEL OF THE SECOND PORTION OF THE CONTINUOUS PATH AND EXTENDING FROM THE FIRST REGION TO THE SECOND REGION, AND INTRODUCING THE DIVERTED LIQUID INTO THE BATH AT SAID SECOND REGION. 